New ticket with same name but other number is no allowed

When someone open a new ticket, there is a 3 fields that you have to fill no metter what : NAME, Phone , Email. But there is a problem with it .

The next time the same person want to open a new ticket with the same name and email (!)but(!) different phone number - it will be opened with the same number as it already saved in the user profile.

For example :

I've opened a ticket with this fields: Name:Alex , EMAIL: av@gmail.com, Phone: 08555213 . Now I can see it

the next time i want to open a ticket with the same fields of name and email but in PHONE i will put something different : 09852888 (for example) - When the ticket is opened,the admin of tickets will see the previous number inside. (08555213) , and there is no some comment or warning that show me a different number.